1. Field of the Invention
The present invention relates to an active geometry control suspension system (AGCS), and more particularly, to an active geometry control suspension system that makes it possible to reduce machining cost and A/S cost by using a track-variable kit that is separately manufactured.
2. Description of Related Art
An active geometry control suspension system that is generally applied to a rear suspension is a device that improves handling performance by improving cornering force of the rear wheel by changing the geometry of the rear suspension, when a vehicle rapidly turns.
The active geometry control suspension system causes oversteer particularly when a vehicle rapidly turns, thereby reducing the steering stability, and the steering stability of the vehicle is improved by applying toe-in to the rear wheel at the outside, when the vehicle rapidly turns, in order to prevent the oversteer.
FIG. 1 is a perspective view showing an example of a common active geometry control suspension system.
Referring to FIG. 1, an active geometry control suspension system includes a lower arm 7 under and between a knuckle 1 at a rear wheel W and a subframe 5 mounted on a cross-member 3.
An upper arm 9 is connected to a side above and between the knuckle 1 and the subframe 5 and an assist link 11 is connected to the other side above and between the knuckle 1 and the subframe 5, together with a node-changeable unit 20.
One end of the assist link 9 is connected to the upper portion of the knuckle 1 through a ball joint BJ and the other end is connected to the subframe 5 through the node-changeable unit 20, thereby forming a vehicle body-sided node P.
FIGS. 2 and 3 are a side perspective view and an internal configuration view of an assist link and a node-changeable unit that are applied to the active geometry control suspension system.
The node-changeable unit 20, as shown in FIGS. 2 and 3, includes a housing with rail-mounting grooves 21, a cam-operating rail 25, a cam 27, rotary levers 29, a motor 31, and a slider 33.
The housing 23 is integrally formed with the subframe 5 and has the arc-shaped rail-mounting groove 21 at both sides.
The cam-operating rail 25 is fixed in the rail-mounting grooves 21 of the housing 23.
The cam 27 is coupled to be slidable up/down on the outer side of the cam-operating rail 25 and connected with the vehicle body-sided connection portion of the assist link 11 by a bolt 35.
The rotary levers 29 are fitted at both sides of the vehicle body-sided connecting portion of the assist link 11, and one end of the rotary lever 29 is hinged to one side of the housing 23 and forms a hinge point H and the other end has a fork 37 and is connected with the slider 33.
The motor 31 includes a reducer 39 and is disposed with a screw shaft, 41, which is a rotary shaft, facing down.
The slider 33 has the center portion thread-fastened to the screw shaft 41 and moves up/down in the rotational direction of the screw shaft 41.
Further, two guide pins 43 are disposed through the slider 33 in the up-down direction and the pins guide the slider 33 moving up/down while preventing the slider 33 from rotating, when the screw shaft 41 rotates.
In addition, fork protrusions 45 are formed at both sides of the slider 33 and fitted in the forks 37 of the rotary levers 29.
Therefore, the active geometry control suspension system applies toe-in to the rear wheel W with bump at the outside, when a vehicle rapidly turns.
That is, when a vehicle rapidly turns and a controller moves down the slider 33 by driving the motor 31, the rotary levers 29 connected to the sliders 33 rotate about the hinge points H.
Accordingly, the vehicle body-sided connection portion that forms the vehicle body-sided node P of the assist link 11 moves down with the cam 27 along the cam-operating rail 25 and moves down the position of the vehicle body-sided node P of the assist link 11.
Therefore, the toe-in value of the rear wheel W at the outside increases and improves stability of turning of a vehicle under the circumstances such as when the vehicle turns at high speed and receives cross wind, and the vehicle suddenly changes the lane, thereby implementing stable travel performance of the vehicle.
However, since the rail-mounting grooves 21 are formed at the housing 23 in the active geometry control suspension system described above, it is also necessary to change the tracks of the rail-mounting grooves 21 when performance tuning is performed while the tracks of the cam-operating rails 25 are changed in the development, it is required to manufacture a new housing 23 every time the tracks change, thereby causing a large amount of cost.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.